Administering Cisco QoS for IP Networks

The business impact of QoS on major enterprises today ensures the delivery of the right information necessary to the bottom-line success of the business. QoS expedites the handling of mission-critical applications, while sharing network resources with non-critical applications. Today, with Cisco products, QoS has finally found its time by effectively providing algorithms to ensure delivery that was once only promised.

Over the past couple of years, the number of methods or protocols for setting quality of service (QoS) in network equipment has increased dramatically. Advanced queuing algorithms, traffic shaping, and access-list filtering, have made the process of choosing a QoS strategy a much more daunting task. All networks can take advantage of aspects of QoS for optimum efficiency, whether the network is for a small corporation, an enterprise, or an ISP.

Contents

• Foreword xxiii

• Introduction 2
• IP Address Classes and Classful IP Routing 2
• Classes A, B, and C 5
• Class D Addresses (Multicast) 8
• RIPv1 and IGRP 10
• Variable-Length Subnet Mask (VLSM) Review 17
• Why Do We Need VLSM? 19
• Standard Access Control Lists (ACLs) 21
• Extended Access Control Lists (ACLs) 25
• Benefits of Extended ACLs 30
• Network Address Translation (NAT) 35
• Controlling NAT with ACLs 39
• Route Maps 40
• Where to Use Route Maps 41
• Summary 43
• FAQs 44

• Introduction 48
• Reviewing Basic Concepts of IGRP 48
• How Does EIGRP Work? 50
• Defining the Four Basic Components of EIGRP 57
• Establishing Protocol-Dependent Modules 57
• Establishing Neighbor Discovery/Recovery 58
• Managing Reliable Transport Protocol 59
• Establishing DUAL Finite State Machine 59
• Implementing Packet Types 60
• Configuring EIGRP's Distributed
• Update Algorithm (DUAL) 64
• Configuring Basic EIGRP 75
• Verifying Configuration with Show Commands 84
• Configuring Advanced EIGRP 87
• Summarizing EIGRP Addresses 88
• Redistributing EIGRP and OSPF 97
• Unequal Cost Load Balancing 103
• Recognizing Caveats 108
• Stuck-in-Active 108
• Auto-Summarization 109
• Troubleshooting EIGRP 110
• Troubleshooting Stuck-in-Active Routes 110
• Troubleshooting Auto-Summarization 115
• Troubleshooting not-on-common-subnet 117
• Summary 119
• FAQs 120

• Introduction 124
• Defining Quality of Service 124
• What Is Quality of Service? 125
• Applications for Quality of Service 126
• Understanding Congestion Management 129
• Defining General Queuing Concepts 130
• Leaky Bucket 131
• Tail Drop 132
• Token Bucket 133
• First In First Out Queuing 134
• Fair Queuing 136
• Priority Queuing 138
• Custom Queuing 139
• Understanding Congestion Avoidance 141
• Congestion Avoidance in Action 142
• Introducing Policing and Traffic Shaping 143
• Traffic Shaping 144
• Summary 145
• FAQs 146

• Introduction 148
• Introducing Type of Services (ToS) 148
• ToS Service Profile 150
• Defining the Seven Levels of IP Precedence 151
• Explaining Integrated Services 152
• Defining the Parameters of QoS 154
• Admission Requirements 155
• Introducing Resource Reservation Protocol (RSVP) 156
• RSVP Traffic Types 157
• RSVP Operation 157
• RSVP Messages 158
• Introducing Differentiated Service (DiffServ) 161
• The DiffServ Code Point (DSCP) 162
• Expanding QoS: Cisco Content Networking 168
• Application Aware Classification: Cisco NBAR 169
• PDLM 174
• Summary 176
• FAQs 178

• Introduction 182
• Configuring Policy-based Routing (PBR) 182
• Using PBR to Route Specific Packet Types 184
• Defining Committed Access Rate (CAR) 185
• Configuring Distributed CAR (DCAR) 188
• Marking and Transmitting Web Traffic 188
• Remarking the Precedence Bit and Transmitting Web Traffic 189
• Marking and Transmitting Multilevels of CAR 190
• Marking and Rate Limiting ISPs 191
• Rate Limiting by Access List 193
• Using CAR to Match and Limit by MAC Address 194
• Monitoring CAR 196
• Configuring Cisco Express Forwarding 196
• Enabling CEF 197
• Monitoring CEF 198
• Troubleshooting Cisco Express Forwarding Caveats and Bugs 200
• Configuring Basic Network-based Application Recognition (NBAR) 201
• Creating an NABR Class Map 202
• Creating a Policy Map 203
• Applying the Policy Map to an Interface 203
• Configuring Complex NBAR 204
• Integrating NBAR with Class-based Weighted Fair Queuing 206
• Creating a Class Map to Identify NBAR 207
• Configuring Class Policy in the Policy Map 207
• Attaching the Policy to an Interface 208
• Configuring NBAR with Random Early Detection 209
• Configuring System Network Architecture Type of Service 211
• Mapping SNA CoS to IP ToS 211
• Prioritizing SNA Traffic 212
• Summary 213
• FAQs 215

• Introduction 218
• Using FIFO Queuing 218
• High Speed versus Low Speed Links 220
• Using Priority Queuing 221
• How Does Priority Queuing Work? 221
• Using Custom Queuing 224
• How Does Custom Queuing Work? 224
• Using Weighted Fair Queuing (WFQ) 228
• How Does Weighted Fair Queuing Work? 228
• Using Random Early Detection (RED) 232
• How Does Random Early Detection Work? 232
• Summary 235
• FAQs 236

• Introduction 240
• Configuring FIFO Queuing 240
• Enabling FIFO 240
• Configuring Priority Queuing 244
• Enabling Priority Queuing 244
• Applying Your Priority List to an Interface 247
• Configuring Custom Queuing 252
• Enabling Custom Queuing 252
• Applying Your Configuration to an Interface 254
• Configuring Weighted Fair Queuing 259
• Enabling Weighted Fair Queuing 259
• Configuring Random Early Detection 263
• Enabling Random Early Detection 263
• Summary 267
• FAQs 268

• Introduction 272
• Using the Resource Reservation Protocol (RSVP) 272
• What Is RSVP? 273
• What RSVP Is Not 275
• How Does RSVP Work? 275
• Why Do I Need RSVP on My Network? 282
• Advantages of Using RSVP 283
• Disadvantages of Using RSVP 283
• Using Class-Based Weighted Fair Queuing (CBWFQ) 284
• How Does CBWFQ Work? 284
• Why Do I Need CBWFQ on My Network? 286
• RSVP in Conjunction with CBWFQ 290
• Using Low Latency Queuing (LLQ) 291
• How Does LLQ Work? 291
• Why Do I Need LLQ on My Network? 294
• Using Weighted Random Early Detection (WRED) 295
• How Does WRED Work? 295
• Why Do I Need WRED on My Network? 298
• Using Generic Traffic Shaping and Frame Relay Traffic Shaping 299
• Token Bucket 299
• How Does GTS Work? 301
• Why Do I Need GTS on My Network? 301
• How Does FRTS Work? 303
• Why Do I Need FRTS on My Network? 305
• Running in Distributed Mode 307
• Features Supported in Distributed Mode 307
• IOS Versions 308
• Operational Differences 308
• Restrictions 308
• Using Link Fragmentation and Interleaving 309
• How Does LFI Work? 311
• How Can This Be Useful on My Network? 313
• Understanding RTP Header Compression 313
• How Does RTP Header Compression Work? 314
• Summary 315
• FAQs 318

• Introduction 322
• Enabling, Verifying, and Troubleshooting Resource Reservation Protocol (RSVP) 322
• Enabling RSVP 324
• Verifying Your RSVP Configuration 324
• Troubleshooting RSVP 327
• Enabling, Verifying, and Troubleshooting Class-Based Weighted Fair Queuing (CBWFQ) 328
• Enabling CBWFQ 328
• Verifying Your CBWFQ Configuration 334
• Troubleshooting CBWFQ 336
• Configuring, Verifying, and Troubleshooting Low Latency Queuing (LLQ) 337
• Configuring LLQ 337
• Verifying Your LLQ Configuration 338
• Troubleshooting LLQ 339
• Configuring, Verifying, and Troubleshooting Weighted Random Early Detection (WRED) 340
• Configuring WRED 340
• Verifying Your WRED Configuration 343
• Troubleshooting WRED 348
• Configuring and Verifying Generic Traffic Shaping (GTS) and Frame Relay Traffic Shaping (FRTS) 349
• Configuring GTS 351
• Verifying Your GTS Configuration 352
• Configuring FRTS 354
• Verifying Your FRTS Configuration 357
• Understanding Distributed Technologies 359
• DCEF 360
• DWRED 360
• Configuring, Verifying, and Troubleshooting Link Fragmentation and Interleaving (LFI) 362
• Configuring LFI 362
• Verifying Your LFI Configuration 365
• Troubleshooting MLP 366
• Configuring, Verifying, and Troubleshooting RTP Header Compression 367
• Configuring RTP Header Compression 368
• Verifying Your RTP Header Configuration 368
• Troubleshooting RTP Header Compression 369
• Summary 370
• FAQs 372

• Introduction 376
• The History of BGP 376
• Exterior Gateway Protocol (EGP) 376
• The Original Implementation 377
• Maximizing the Functionality of BGP 380
• The BGP Routing Process 380
• External BGP and the Internet 393
• What Is an Autonomous System? 395
• The BGP Path Selection Process 402
• BGP Path Selection Example 403
• Redistributing BGP into Your IGP 408
• Redistributing the Default Route 409
• Defining Internal BGP, Route Reflectors, and Confederations 411
• Internal BGP 412
• Advanced BGP Network Design 414
• Building Network Redundancy 415
• Summary 418
• FAQs 419

• Introduction 422
• Relevant RFCs 422
• Enabling BGP Routing 423
• Defining BGP for an Autonomous System 424
• Defining the Remote AS 425
• Public versus Private Autonomous Systems 426
• Enabling BGP Routing 426
• Configuring EBGP Neighbors 427
• Configuring IBGP Neighbors 432
• Peering to Loopback Interfaces 432
• Configuring Route Reflectors 433
• Configuring Confederations 436
• When Do I Need Route Reflectors and Confederations? 438
• Weight, MED, LOCAL PREF, and Other Advanced Options 439
• Route-Map, Match, and Set Commands 441
• Weight Attribute 442
• Multiexit Discriminate (MED) Attribute 444
• Local Preference Attribute 446
• AS_Path Attribute 448
• Origin Attribute 449
• Next_Hop Attribute 449
• Summary 454
• FAQs 455

• Introduction 458
• Understanding MPLS 458
• Label Switching Basics 460
• Integrating MPLS into QoS 470
• Ensuring MPLS Is Efficient and Reliable 470
• Standardizing MPLS for Maximum